Fix crash in additional_fanout when calling traverse

Summary: As above

Reviewed By: alikhtarov

Differential Revision: D59609681

fbshipit-source-id: 6b4b1f942957451fe3f6e062a0410327bb3ee139

mcrouter/ServiceInfo-inl.h

@@ -51,19 +51,21 @@ class RouteHandlesCommandDispatcher {
  public:
   bool dispatch(
       size_t typeId,
+      const std::shared_ptr<ProxyRequestContextWithInfo<RouterInfo>>& ctx,
       folly::StringPiece key,
       const ProxyRoute<RouterInfo>& proxyRoute,
       std::string& outStr) {
-    return dispatcher_.dispatch(typeId, *this, key, proxyRoute, outStr);
+    return dispatcher_.dispatch(typeId, *this, ctx, key, proxyRoute, outStr);
   }
 
   template <class Request>
   static void processMsg(
       RouteHandlesCommandDispatcher<RouterInfo>& me,
+      const std::shared_ptr<ProxyRequestContextWithInfo<RouterInfo>>& ctx,
       folly::StringPiece key,
       const ProxyRoute<RouterInfo>& proxyRoute,
       std::string& outStr) {
-    outStr = me.processMsgInternal<Request>(key, proxyRoute);
+    outStr = me.processMsgInternal<Request>(ctx, key, proxyRoute);
   }
 
  private:
@@ -73,13 +75,15 @@ class RouteHandlesCommandDispatcher {
       // Dispatcher class
       detail::RouteHandlesCommandDispatcher<RouterInfo>,
       // List of types of args to Dispatcher::processMsg()
+      const std::shared_ptr<ProxyRequestContextWithInfo<RouterInfo>>&,
       folly::StringPiece,
       const ProxyRoute<RouterInfo>&,
       std::string&>
       dispatcher_;
 
   template <class Request>
   std::string processMsgInternal(
+      const std::shared_ptr<ProxyRequestContextWithInfo<RouterInfo>>& ctx,
       folly::StringPiece key,
       const ProxyRoute<RouterInfo>& proxyRoute) {
     std::string tree;
@@ -111,6 +115,7 @@ class RouteHandlesCommandDispatcher {
     } else {
       request.key_ref() = key;
     }
+    fiber_local<RouterInfo>::setSharedCtx(ctx);
     proxyRoute.traverse(request, t);
     return tree;
   }
@@ -411,8 +416,10 @@ ServiceInfo<RouterInfo>::ServiceInfoImpl::ServiceInfoImpl(
             requestName, typename RouterInfo::RoutableRequests());
 
         std::string res;
+        auto ctx = ProxyRequestContextWithInfo<RouterInfo>::createRecording(
+            proxy_, nullptr);
         if (!routeHandlesCommandDispatcher_.dispatch(
-                typeId, key, proxyRoute_, res)) {
+                typeId, ctx, key, proxyRoute_, res)) {
           throw std::runtime_error(
               folly::sformat("route: unknown request {}", requestName));
         }

mcrouter/lib/HashSelector.h

@@ -97,7 +97,9 @@ class BucketHashSelector : public HashSelectorBase<HashFunc> {
     auto key = folly::to<std::string>(*bucketId);
     if (this->clientFanout_) {
       auto& ctx = mcrouter::fiber_local<RouterInfo>::getSharedCtx();
-      key += ctx->userIpAddress();
+      if (ctx) {
+        key += ctx->userIpAddress();
+      }
     }
     return folly::fibers::runInMainContext(
         [this, size, key]() { return this->selectInternal(key, size); });